This invention relates to lead-acid storage battery plates and to curing reels of the stock used to make such plates.
Pb-acid storage battery plates comprise an active material embedding a conductive framework (i.e. the grid). The grid includes a current collecting border, and a network of lead alloy grid wires extending from the border and defining a plurality of cells for retaining the active material. In the continuous strip method of making battery plates, a continuous strip of the grid material is fed through a pasting apparatus where a leady (i.e. principally PbO) active material paste is applied to the grid. In addition to the PbO, the paste typically contains about 14% by weight water and about 20% or more by weight metallic lead particles. This pasting process may be performed in a number of different ways depending on the particular type of equipment used by the manufacturer. Following pasting, the strip is cut into individual plates which are flash-dried to about 9%-12% water in order to prevent the plates from later sticking to each other. The plates leave the drying oven singly, or in pairs, and are transferred to a shingling conveyor where the plates are stacked together in overlapping, shingle-like, fashion. From the shingling conveyor the plates are scooped up in groups by an operator and hand-stacked onto a pallet. The pallet is then moved by fork-lift to a curing area. The curing process involves storage of the plates for a period of time under controlled temperature and humidities and may, in some circumstances, involve steaming of the plates. During curing, the metallic lead particles are oxidized to lead oxide (an exothermic reaction) which heats up the plates and promotes further drying. At the end of cure, the residual metallic lead and moisture content of the plates is about 2% each. Following curing, the plates are hand-loaded off the curing pallets and into appropriate battery assembly apparatus. In the dried condition the plates are very suscepticle to damage due to rough handling. Even the mere flexing of the plate can cause random cracking of the paste, primarily at the interface between the paste and the grid wires. This cracking causes resistance to electron transfer through the active material and between the active material and the grid surface. In severe situations, the cracking can cause loss of the active material from the grid.
The speed of the above described process is limited by the rate at which the plates can be manually stacked, and later unstacked. It would be desirable to provide a process which is faster, less expensive and less manual labor dependant. It would be even more desirable if a faster, more economical process could be developed which also produces a better plate.
Accordingly it is an object of the present invention to provide a faster, less labor dependant process for curing Pb-acid storage battery plates and thereafter preparing them for assembly into batteries. Another object of the present invention is to provide a Pb-acid storage battery plate offering increased electrolyte availability and exposure to the plate's active material. These and other objects and adantages of the present invention will become more readily apparent from the detailed description thereof which follows.